1. Field
The present disclosure relates generally to rockets and, in particular, to managing the operation of a rocket. Still more particularly, the present disclosure relates to a method and apparatus for detecting internal configuration changes that may occur during the operation of a rocket.
2. Background
A rocket is a vehicle that has a rocket engine used for thrust. For example, a rocket may be a missile, a spacecraft, an aircraft, or other vehicle that has a rocket engine.
During flight, a rocket may undergo internal configuration changes. A change to the internal configuration of a rocket is a change in the structure of the rocket. A change to the internal configuration of the rocket may include, for example, bending of the structure of the rocket along a longitudinal axis of the rocket. This type of bending may be referred to as vibrations, bending modes, and other types of changes to the internal configuration of the rocket.
These internal configuration changes may be interpreted by a navigation control system in the rocket as a change in the direction of flight of the rocket. For example, a bending along the length of the rocket may cause a change in the position of a tip of the rocket such that the rocket temporarily points the wrong direction, although the rocket is actually traveling in the correct direction.
As a result, the navigation control system may attempt to correct the direction of the rocket based on the perceived errors in the direction of travel. Performing these types of corrections when they are unnecessary may increase the fuel usage more than desired.
Further, with the use of different types of engines, performing unnecessary corrections may deplete the pressurized fluid used to steer these engines. For example, with a Vernier engine, performing unnecessary corrections may prematurely deplete the Vernier blow down fluid that is used to steer the engine. Over-corrections also may result in undesired operation of the rocket.
Currently, mechanical devices are used to identify the bending of a rocket. These mechanical devices may be part of an internal configuration detection system. For example, a gyroscope may be mounted on the rocket. The gyroscope may detect these changes and send the information about the detected changes to the navigation control system. In this manner, the navigation control system may take this information into account when controlling the direction in which the rocket travels.
Although gyroscopes may be useful, these gyroscopes are typically mounted at locations where the greatest amount of deflection occurs when the rocket bends. These locations may be inconvenient locations. For example, when the rocket takes the form of a launch vehicle, these locations may be on a fuel tank, such as a liquid oxygen fuel tank. As a result, the gyroscopes cannot be directly connected to the fuel tank. Additional mechanical devices are needed to mount the gyroscopes to provide a temperature neutral environment at these locations. Further, these additional mechanical devices also are selected to isolate the gyroscopes from vibrations and motions not related to the bending of the rocket.
As a result, this type of internal configuration detection system may be more complex, larger, heavier, and more expensive than desired. Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.